(1) Field of the Invention
The invention relates to a method and a device for the division of single crystals, an adjusting device and a test method for the determination of an orientation of a single crystal for such a method.
(2) Description of Related Art
Single crystals produced by crystal pulling are divided into individual disks known as wafers for use in semiconductor technology. Known cutting methods are inner hole sawing and wire cutting. The cutting forces occurring in the division of single crystals result in lateral deflection of the rotary cutting disk in the case of inner hole sawing or of the wire in the case of wire cutting. As a result of this wafers of nonuniform thickness are produced or the surface exhibits other irregularities, e.g., warp and bow. In the case of silicon single crystals the predominant problem occurring is corrugation of the surface. This results in a reduction in quality in the wafers produced and hence in a lower yield of high-quality wafers.
To solve this problem it is known in the case of inner hole sawing to measure the deflection of the cutting disk and to correct this by the action of compressed air. This method, however, has the disadvantage that a film of coolant applied for cooling the cutting disk is affected by the compressed air and this in turn has an effect on cooling during cutting. It is, furthermore, known to set the single crystal in a mounting which is specially shaped in order to counteract the forces occurring in the deflection of the cutting disk with opposing forces for compensation. In wire cutting no active influence on the deflection of the wire is possible.